1435 research outputs found
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Non-Abelian Vortices of Higher Winding Numbers
No full textWe make a detailed study of the moduli space of winding number two (k=2)
axially symmetric vortices (or equivalently, of co-axial composite of two
fundamental vortices), occurring in U(2) gauge theory with two flavors in the
Higgs phase, recently discussed by Hashimoto-Tong (hep-th/0506022) and
Auzzi-Shifman-Yung (hep-th/0511150). We find that it is a weighted projective
space WCP^2_(2,1,1)=CP^2/Z_2. This manifold contains an A_1-type (Z_2) orbifold
singularity even though the full moduli space including the relative position
moduli is smooth. The SU(2) transformation properties of such vortices are
studied. Our results are then generalized to U(N) gauge theory with N flavors,
where the internal moduli space of k=2 axially symmetric vortices is found to
be a weighted Grassmannian manifold. It contains singularities along a
submanifold
On a simple storage scheme for strings achieving entropy bounds
No full textIn this note we propose a storage scheme for a string S[1,n], drawn from an alphabet A, that requires space close to the k-th order empirical entropy of S and allows to retrieve any L-long substring of S in optimal O(1 + L log A/log n) time. This matches the best known bounds via the only use of binary encodings and tables
EXOR Projected Sum of Products
No full textIn this paper we introduce a new algebraic form for Boolean function representation, called \emph{EXOR-Projected Sum of Products} (\emph{EP-SOP}), resulting in a four level network that can be easily implemented in practice. We prove that deriving an optimal EP-SOP from an optimal SOP form is a hard problem (-hard); nevertheless we propose a very efficient approximation algorithm, which returns in polynomial time an EP-SOP form whose cost is guaranteed to be near the optimum. Experimental evidence shows that for about of the classical synthesis benchmarks the EP-SOP networks have a smaller area and delay with respect to the optimal SOPs (sometimes gaining even - of the area). Since the computational times required are extremely short, we recommend the use of the proposed approach as a post-processing step after SOP minimization
Design and implementation of SATOR: a Web service aggregator
No full textThe aggregation methodology we propose in this paper automatically generates the service contract of a composite service from a set of contracts to be ggregated together with a data-flow mapping linking service parameters. Service contracts consist of (WSDL) signature, (OWL) ontology information, and (YAWL) behaviour specification.
The aggregation process generates the workflow of the composite from the initial workflows by suitably adding control-flow constraints among their tasks due to data-flow dependencies among task parameters.
After describing the whole methodology, we will also give an insight on our proof-of-concept Java prototype implementation of the aggregation process
Il progetto di restauro: valore culturale e questione sociale
Get PDFGli interventi e l’azione dell’uomo quanto del tempo sui prodotti della natura (le scogliere, le sculture prodotte dall’erosione del vento e dell’acqua) e dell’attività umana (architettura, pittura, scultura, etc..), da un lato hanno contribuito ad arricchire i valori propri delle singole opere, dall’altro sono stati anche causa di disgregazione, di menomazione, di perdita di significati estetici e cultural
I servizi bibliotecari e la formazione a distanza. Seminario 2 ottobre 2006
No full textRIASSUNTO: La progettazione e l'erogazione di una formazione didattica a distanza implica notevoli cambiamenti nei tradizionali servizi di biblioteca. SUMMARY The progectation and the allocation of the e-learning involve remarkable changements in the traditional services of the libraries
Università, scienza e politica nel Conflitto delle facoltà di Kant
No full textRIASSUNTO Il saggio è uno studio dedicato alla posizione di Kant in merito alla funzione pubblica dell'università e al rapporto tra potere politico e comunità scientifica, a partire da un'analisi del saggio "Il Conflitto delle facoltà" (1798). SUMMARY This article is devoted to analyse Kant's Thought on University, Science and Politics as developed in the late essay "The Conflict of Faculties" (1798)
Canonical elements for Opik theory
No full textSUMMARY The purpose of this paper is to find a set of canonical elements to use within the framework of O¨ pik theory of close encounters of a small body with a planet (O¨ pik, Interplanetary Encounters, 1976). Since the small body travels along a planetocentric hyperbola during the close approach and O¨ pik formulas are valid, without approximations, only at collision, we derive a set of canonical elements for hyperbolic collision orbits (eccentricity e→1+, semi-major axis a fixed) and then we introduce the unperturbed velocity of the small body and the distance covered along the asymptote as a new canonically conjugate pair of orbital elements. An interesting result would be to get a canonical set containing the coordinates in the Target Plane (TP), useful for the analysis of the future encounters: in the last part we prove that this is not possible
Chaotic ratchet dynamics with cold atoms in a pair of pulsed optical lattices
No full textSUMMARY We present a very simple model for realizing directed transport with cold
atoms in a pair of periodically flashed optical lattices. The origin of this
ratchet effect is explained and its robustness demonstrated under imperfections
typical of cold atom experiments. We conclude that our model offers a clear-cut
way to implement directed transport in an atom optical experiment
Confining properties of 2-color QCD at finite density
No full textWe study the confining properties of QCD with two colors across the finite
density phase transition. A disorder parameter detecting dual superconductivity
of the QCD vacuum is used as a probe for the confinement/deconfinement phase
transition